Ticket #2163: rotating dash is not removed when mc finishes reading the directory

...or when other long aperation is finished.

(rotate_dash): add argument to show/hide dash. Move dash to the corner
of the right/top panel from corner of the screen.

Thanks Egmont Koblinger for the original patch.

Signed-off-by: Andrew Borodin <aborodin@vmail.ru>
(find_rotate_dash): invert the boolean argument

...to be consistent with the new rotate_dash() behavior and to be
intuitive.

Signed-off-by: Andrew Borodin <aborodin@vmail.ru>
Merge branch '2163_rotating_dash'

* 2163_rotating_dash:
  (find_rotate_dash): invert the boolean argument
  Ticket #2163: rotating dash is not removed when mc finishes reading the directory